1. Field of the Invention
The present invention relates to a method and apparatus for the disposing of fly ash by mixing said fly ash with a wetting agent to form a dustless slurry.
2. History of the Prior Art
The disposal of fly ash residue from coal fired power plants, incinerators and the like has consistently been a problem over the years. This problem is growing both in quantity and complexity due to the increased usage of coal burning power plants which have come into being because of the scarcity of petroleum products and the continued opposition to the construction of nuclear power plants. Considerable attention has also been drawn to the environmental impact of disposing of fly ash. Fly ash has been typically considered a waste material incident to the burning of coal although there are many uses of the fly ash residue in the area of manufacturing fertilizer materials and as an additive to cement products.
The fly ash is a wispy material and is typically prevented from being carried off with the exhaust gases of the furnace by the use of fly ash collection means such as electrostatic precipitators or bag houses. Fixed containers or silos for holding the fly ash are usually constructed in the proximity of the coal burning furnaces for holding the fly ash until it can be disposed of.
In order to handle this wispy material often times it is removed and mixed with a wetting solution to form a slurry and this slurry is then pumped into molds for hardening or into slurry disposal ponds. Minimal water is required to produce a slurry which sets up without surplus water when the disposal site's ecological considerations require no surplus water such as underground disposal. However, other wetting agents, such as acids, may be utilized to produce approximately the same effect, however, when the acid is mixed with the fly ash, which is high in mineral oxides, a reaction typically takes place which tends to neutralize the acids, hence, often solving two problems at the same time, namely, the disposal of waste acids and the disposal of fly ash.
One inherent problem in producing a slurry is that if a slurry is mixed too wet, some particles will become suspended in the slurry rather than forming a part of the hardened cake, and upon drying will reproduce an ash that can escape into the atmosphere and become an atmospheric pollutant.
On the other hand, if the slurry is mixed too dry, some of the wispy particles may escape creating a dust atmosphere, which, again, is an atmospheric pollutant. Another problem in mixing the slurry too dry is that of caking in the mixture in disposal pipes which ultimately clogs the pipe requiring complete cleaning thereof.
In summary, the fly ash must be constantly removed from the furnaces and must be handled very carefully lest it become an atmospheric pollutant.